Citronella Ants

Lasius

Classification

Phylum: Arthropoda
Subphylum: Hexapoda
Class: Insecta
Order: Hymenoptera
Superfamily: Formicoidea
Family: Formicidae
Subfamily: Formicinae
Tribe: Lasiini
Genus: Lasius

Pronunciation

How to pronounce Lasius: //ˈlɑːsiəs//

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Images

Lasius (Chthonolasius) pilosus by the Smithsonian. Used under a CC0 license.

Lasius (Acanthomyops) pogonogynus by the Smithsonian. Used under a CC0 license.

Lasius alienus illyricus by the Smithsonian. Used under a CC0 license.

Lasius (Acanthomyops) plumopilosus by the Smithsonian. Used under a CC0 license.

Summary

Lasius is a genus of formicine ants that includes various species commonly found in temperate habitats. Known for their mutualistic relationships with aphids and their fondness for honeydew, these ants are significant members of their ecosystems. Certain species are colloquially referred to as moisture ants due to their nesting preferences.

Physical Characteristics

Common brown to yellow ants, workers measuring 2.5-4mm, males 3-4.5mm, queens 4-9mm. They have a short, somewhat upwardly sloped dorsal propodeal surface and a notably longer posterior declivitous face. Flexor surfaces of the middle and hind tibiae usually lack pilosity, but if present, the hairs are not arrayed in two parallel rows.

Identification Tips

Workers are monomorphic, measuring 2 to 3 mm in length, yellow to dark brown. They can be distinguished from carpenter ants (Camponotus) by their smaller size and a notch in the dorsal thorax, while carpenter ants have a rounded thorax.

Habitat

Temperate Northern Hemisphere forests and grasslands, typically in mesic habitats; some species are also found in fens and bogs. Many species, commonly referred to as moisture ants, make nests in moist rotting wood or under rocks.

Distribution

Widespread, with numerous species found in North America and other parts of the Northern Hemisphere.

Diet

Many or all subterranean species have mutualistic relationships with root-feeding aphids, and all species are fond of honeydew. Epigeic species also gather extrafloral nectar and prey on small insects as well.

Life Cycle

Workers forage throughout the frost-free season, with mating flights for some species occurring from July to early October. Queens of some parasitic species may be found above ground in the spring after mating in the fall.

Reproduction

Just-mated Lasius queens can found colonies independently after mating in the air, sealing themselves in a small nest in soil or rotting wood. Many parasitic species require entry into a host colony for brood rearing.

Ecosystem Role

Many Lasius species have mutualistic relationships with root-feeding aphids, playing a role in their population management. They also contribute to nutrient cycling by scavenging dead insects and organic matter.

Economic Impact

Moisture ants can infest buildings, particularly foundation forms contacting the soil, but they are not considered a structural threat as they only make galleries in already decayed wood.

Cultural Significance

In the Alps, the grassy hillocks built by Lasius flavus are historically used by goatherds as natural compasses due to their eastward alignment.

Similar Taxa

Camponotus (carpenter ants)
Acanthomyops (citronella ants)

Misconceptions

While moisture ants can infest buildings, they are not a structural threat unlike other wood-damaging insects like termites or carpenter ants.